This invention relates to compositions for washing and cleaning purposes which contain biodegradable and ecologically acceptable builder substances, to the use of these builder substances and to a method for washing and/or cleaning.
Builders (so-called detergent intensifiers) are of central importance for the running of the washing and cleaning operation. The function of the builders is primarily to eliminate from the washing or cleaning process the calcium and magnesium ions originating partly from the water, partly from dirt or for instance from textiles, by forming complexes or ion exchange and to support the action of surfactants. Modern builders therefore must satisfy a number of suitability criteria.
Besides the already mentioned complexing or ion exchange function for alkaline earth ions, builders should have a certain primary washing or cleaning action. This is understood to mean, for instance, a good specific washing and cleaning action for pigments and fats, or, for instance, a good washing action for certain textile fibers, the improvement of the surfactant properties and a favorable effect on the foaming properties. In particular, in addition to the aforementioned functions the builders should contribute substantially to the dispersion of dirt in washing and cleaning solutions. This means, for example, that greying and yellowing of the textiles to be washed is inhibited, which is very important for good successful washing.
As secondary properties, builders should demonstrate a good dirt-carrying capacity and prevent incrustation on textiles. Furthermore, they should also prevent corresponding deposits in washing machines and exhibit desirable, e.g. non-corrosive, behavior.
Furthermore, the builder substances should be chemically resistant, technically easy to process, non-hygroscopic, stable during storage and compatible with other constituents of washing and cleaning compositions. They should also have satisfactory color and odor qualities and be based on safe raw materials.
Besides human-toxicological harmlessness, the builder substances should furthermore be harmless to the environment, biodegradable, and last but not least, also meet economic requirements.
Builder substances known in the prior art include, for example, certain washing alkalis (such as soda, sodium silicate or sodium monophosphate), complexing agents (such as sodium diphosphate, sodium triphosphate, phosphonic acid derivatives, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), citric acid, O-(carboxymethyl)malic acid) or ion exchangers (e.g. zeolites).
Washing alkalis such as soda or monophosphate are currently regarded as technically outmoded because they produce precipitates with the calcium and magnesium salts (so-called hardness salts) of tap water which collect on the washing and equipment as unwanted and troubling deposits. In contrast, currently used builder substances no longer precipitate hardness salts from the water, but eliminate them by forming complexes or by ion exchange. However, the phosphates used as complexing agents contribute to the eutrophication of stagnant or slow-flowing water. The ecological consequences which accompany the use of phosphates are undesirable and have led to an intensive worldwide search for suitable substitutes. However, known substitutes also have a number of drawbacks, since on one hand, like NTA or EDTA, for instance, they are poorly biodegradable, or on the other hand, like citric acid or O-(carboxymethyl)malic acid, they have a comparatively low dispersing power and only a moderate primary washing action. Ion exchangers such as zeolites again demonstrate very pronounced ion exchange abilities, but from an ecological point of view this can be objectionable with regard to heavy metal ions. Furthermore, in order to support the ion exchange taking place in the heterogenous phase, it is necessary to use the zeolites in combination with water- soluble complexing agents (for instance the aforementioned, but objectionable complexing agents such as NTA or EDTA) or carboxylic acid polymers (utilization of the so-called carrier effect). It is also a disadvantage that zeolite crystals may act as a condensation surface for poorly soluble compounds in the washing or cleaning solution, and that they exhibit hardly any dispersing action.